3. A typo for "holding"
(= to keep investing) which morphed into the backronym HODL ("hold on for dear life"). Essentially it means "to keep investing in crypto currencies without fear of losing everything when the bubble bursts".

4. Fear, uncertainty and doubt; a propaganda strategy used to scare people into doing things.

Translations (c) by me, permission for use on lyricstranslate.com and private "fair use" cases granted.